Pressure indicating means for tires



D 10, 1'940- v. M. PYATT 2,224,798

PRESSURE IDICATING MEANS FOR TIRES Filed March 24, 1 938 2 Sheets-Sheetl Dec. 10, 1940. Yv. M. PYA-r'r 2.224.798

PRESSURE INDICATING MEANS FOR TIRES Fgled March 24, 1938 2 lSheets-Sheet2 I V'lipyall y' Patented Dec. 10, 1940 UNITED STATES PATENT OFFICEPRESSURE INDICATING MEANS FOR TIRES l Valdis M. Pyatt, Great Falls,Mont.

with the inner tube thereof, a rheostat `associated with the pressurecontrolled element and over which moves a contact finger operated bysaid l element, the rheostat in turn controlling an electricallyoperated indicator connected in circuit with a rheostat and individualto that particular tire and located preferably on the instrument boardto thus provide means whereby the driver can see at a glance thepressure carried on any particular tire of his vehicle and thus avoideither dangerous over-pressure, as in hot summer weather, or equallydangerous under-pressure.

Other objects will appear in the course of the following description.

'My invention is illustrated in the accompanying drawings wherein:

Fig. 1 is a top plan view of an automotive vehicle showing my inventionapplied thereto, the gure being largely diagrammatic;

Fig. 2 is a side elevation of an automobile wheel showing my structureapplied thereto;

Fig. 3 is a front elevation of the rheostat and .controlling meanstherefor and the support upon which it is mounted, and a sectional viewof a wheel, the ligure showing diagrammatically the electricalconnections to a pressure indicating device;

Fig. 4 is a vertical section on the line 4-4 of Fig. 3, and through thewheel rim and inner tube only those parts of the rheostat actually cutthrough by the section line being shown;

Fig. 5 is a 'section on the line 5-5 of Fig. 3; Fig. 6 is a section onthe line 6--6 of Fig. 3. 5 Referring to these drawings, I0 designatesthe y rim of an automobile wheel, II the shoe of the tire and I2 theinner tube thereof. Extending through the rim and engaging with thisinner tube is the tire valve I3, which may be either a special valve orthe usual inflating valve. As illustrated, this valve I3 is providedwith a laterally extending port I4. Surrounding the outer end of thevalve I3 and disposed preferably in a. recess or chamber I5 in the rimIII, is a base I8 u having an opening I1 through which the outerApplication March 24, 1938, Serial N0. 197,939

" z claims. (c1. :aol-4s) end of the valve I3 projects. Upon this basethere is disposed a Bourdon tube I8, one end of the' tube communicatingwith the port I4. The other end of the tube is carried in a guide I9shown in Fig. 2, which permits the free end of the tube 5 to shiftradially outward or inward from the center of the base I6. Disposedwithin the casing I5 is a rheostat designated generally 20, andoperating over the face of the resistance thereof is an arm 2I mountedon the base I6 for oscillating 10 movement at 22 and at this pointprovided with the gear wheel 23. A spring 24 urges the arm 2| in onedirection. Pivoted at 25 upon the base I6 is a lever 26 carrying on it asegment gear 21 which engages with the gear 23. The end of the 15 tubeI8 is connected to the adjacent end of the lever 26 by means of a curvedlink 28 which is operatively plvoted to the end of the tube I8 and tothe end of the lever 26. It will be seen that when the tube expandsunder pressure, the le- 20 ver 26 will be shifted in one direction, butwhen the tube I8 contracts, it will be shifted in the other direction.This will shift the free end. of the arm 2| over the face of therheostat 20.

The rheostat 20, as shown in Fig. 3, includes 25 a rubber or hard nbresupporting member 23 upon which is mounted the resistance wire 30,connected at intervals to silver inlays or contact pieces 3l, mounted inthe hard fibre support. The arm 2I is also provided at its free end with3o a silver contact member 32 which moves over the faces of the contactpieces 3|. The wire 33 is connected to a collector ring 34 of copper,which is mounted upon a disk 35-rotating with the wheel. Also disposedon the disk 35 is an inner 35 collector ring 36 which is of copper andinsulated from the ring 34. The wire 33 from one end of the rheostat isconnected to the ring 34 while a wire 31 from the ring 36 iselectrically connected rby any suitable means to the arm 2l. Associatedo with the ring 34 is a trolley wheel 38 constituting a brush andcarried by the brake drum housing 33. This trolley wheel or brush isconnected by a Wire 40 to an indicating member on the dash- "strumentbeing individual to the particular tire 50 electrically connectedtherewith. The ammeter 42 is connected in turn to the ground. A batteryor other source of potential 43 is connected in a circuit which includesthe ammeter or other measuring instrument and the rheostat.

` It will be obvious now that as the pressure increases within the innertube of the tire, the arm 2| will move over the rheostat and cut outresistance which will cause the movement of the hand on the amineter,the ammeter having indications thereon showing pounds of pressure. Asthe pressure reduces the inner tire, the arm 2| will move in theopposite direction under the action of the spring 24 and contacting tubeI8 and resistance will be cut in and the hand on the ammeter will showthis reduction in pressure. It

' is to be understood that there are as many of electrical contact.

these indicators 42 as `there are tires and that each indicator willshow the pressure in a particular tire.` Y

It will be noted that the base I6 is located on the valve stem veryclosely adjacent the inner tube or as close to the inner tube aspossible, and

that this is particularly important due to centrifugal force. Thus theBourdon tube with its associated parts will be submitted to almostexact- 1y the same action as the inner tube itself and thus willaccurately register the variation in pressure in the' inner tube. Thispressure-operated mechanism is contained Within the housing, and beinglocated within the recess in the rim of theA tire, it cannot be damagedby mud, rocks or the like. Preferably the contact point or element 32and -the contact pieces 3| of the rheostat are of silver so that athoroughly good contact may be made between these highly conductiveelements. The faces of thecopper rings 34 and 36 may also be plated withsilver if desired, and the peripheries of the contacttrolleys or wheelsmight also be of silver, thus insuring a first-class It is to beunderstood that in case of dual tires, an indicator operating mechanismsuch as shown in`Fig. 3.will go on each tire. A single collector ringmay be used for the ground connection, but a second collector ring 34must be used for each tire. It is to be understood that the base IB isto beso disposed that the arm 2| moves transversely of the planeof thewheel so that the centrifugal force will only tend to make a greatercontact pressure between the contact member 32 and the faces of therheostat elements. The

- Bourdon tube will be preferably made of brass so rheostat and theirconcomitant parts, are all enclosed within a casing 44 which may beattached to the rim I0 of thewheel orformed integrally therewith onwheels that are built for the invention as illustrated in Figs. 2 and 4.In either event the casing 44 is water and dust-proof and is providedwith a lid 45 secured to the body portion of the casing by detachablefastening devices of any desired character, a packing or gasket plate ordisk 46 being provided back of the lid or cover 45 so as to make thedevice water and dust-proof as abovementioned. The cover plate 45 ismanifestly formed with an opening in it for the air valve to pass thruas best illustrated in Fig. 4,' and preferably I provide a nut 41 todraw the shoulders of the air valve tight against the cover plate.

Preferably also the Bourdon tube I8 is con- `permits the parts to bereadily `disassembled as it is only necessary to unfasten and remove thecover plate 45 and the packing disk 46 to obtain access to the Bourdontube and its detachable connection with the air valve I3.

While I have illustrated what I believe to be a particularly practicalform of my invention, I do not Wish to be limited to the details ofconstruction as these might be varied in many ways Without departingfrom the spirit of the invention as deined in the-appended claims.

What is claimed is: 1. Inv an electric circuit controlling mechanism ofthe character stated, the combination with a metallic wheel rim and apneumatic tire thereon including'an-inner tube, of a casing carried bythe rim between'the periphery and the radial supported upon the outerside of the casing,

means pivotally supporting the arm at its other end for oscillation onan axis extending substantially radially of the wheel, and meansoperatively connecting the free end of the Bourdon tube with the arm forcausing the oscillation of the arm as the Bourdon tube expands andconthe inner side of the casing whereby it will be urged more firmlyinto contact with the resistance by centrifugal action upon rotation Yofthe wheel. Y

2. In an electric circuit controlling mechanism of the character stated,thecombination with a metallic wheel rim and a pneumatic tire thereon,including an inner tube, of a casing including a radially impressedportion of the rim and disposed between the peripheryoftherim and theradial center and having radially spaced inner and outer sides, the saidinner side of 'the casing forming a removable cover, a Bourdon tubemounted within the casing, the said inner tube i tracts, the arm lyingbetween the resistance and having an air valve tube extending therefromthrough the casing and through the inner and outer sides thereof, aconnection between an vend of the Bourdon tube and said valve tube bywhich communication is established between the Bourdon tube and theinterior of the tire inner tube, j

a rheostat housed within the casing and including a conductive arm and aresistance over which an end of the arm moves, said resistance beingVsupported in the casing at the outer side thereof, meanspivotallysupporting the arm at its other end for oscillation upon anlaxis extending substantially radially of the wheel, and means opyeratively Vcoupling the free end of the Bourdon tube with the arm Aforcausing the oscillation of the arm on said axis as the Bourdon tubeexpands and contracts, the arm being disposed be-

